03-11-2012, 10:30 AM
Error Analysis and Graph Drawing
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Introduction:
It is impossible to do an experimental measurement with perfect accuracy. There is
always an uncertainty associated with any measured quantity in an experiment even
in the most carefully done experiment and despite using the most sophisticated
instruments. This uncertainty in the measured value is known as the error in that
particular measured quantity. There is no way by which one can measure a quantity
with one hundred percent accuracy. In presenting experimental results it is very
important to objectively estimate the error in the measured result. Such an exercise
is very basic to experimental science. The importance of characterizing the
accuracy and reliability of an experimental result is difficult to understate when we
keep in mind that it is experimental evidence that validate scientific theories.
Likewise, reliability and accuracy of measurements are also deeply relevant to
Engineering.
The complete science of error analysis involves the theory of statistics (see Ref.
1,2) and is too involved to present here. This short presentation is intended to
introduce the student to some basic aspects of error analysis and graph drawing,
which it is expected that the student will then put into practice when presenting
his/her results of the coming experiments.
Use of graphs in experimental physics:
In practical physics, the graph of the experimental data is most important in
improving the understanding of the experimental results. Moreover from the graphs
one can calculate unknowns related to the experiments and one can compare the
experimental data with the theoretical curve when they are presented on same graph.
There are different types of graph papers available in market. So, one should choose
the appropriate type of graph paper to present their experimental results in the best
way depending upon the values of the experimental data and the theoretical
expression of the functions. To understand all those some of the assignments are
given below in addition to those we discussed before.